Boron hydride salt-hydrazine system



United States The present invention relates to a reaction system or mixture of the type used to provide the propulsive force for rockets, missiles, etc.

Countless materials have been proposed and tested as propellants, but very few have been found to possess, to a sufiicient degree, the properties esential for operability. One of the principal difliculties encountered by prior workers in this area has been the variation in the pressure and heat generation of the materials tested. Aside from the disadvantage of nozzle erosion due to such variations, the explosive nature of the materials (which is, of course, a necessary property of propellants) often resulted in variations so violent that the rocket was destroyed. Alternatively, the reaction may follow a path leading to undesirable by-products which in turn would reduce the theoretically available ener y.

An important feature of the present invention is that it provides a reaction system or mixture containing an additive which moderates the pressure and heat generation of the reaction system or mixture such that it will be sufficiently constant to permit the use of the reaction system or mixture as a rocket or missile fuel.

Another important feature of the present invention is that the substance added to the reaction system or mixture has, itself, propulsive properties.

Briefly stated, the present invention comprises the addition of a lithium borane, LiB l-I or the combination of this lithium borane with hydrazine or the combination of LiBJ-L, with pentaborane-9, 135%, to a reaction system or mixture comprising pentaborane-9 and hydrazine. The LiB I-L; is added in amount sufiicient to prevent the entire system from exceeding the decomposition temperature threshold of hydrazine.

An object of the present invention is to provide a reaction system or mixture which does not generate pressure and heat so violently that destructive explosions occur.

Another object of the present invention is to provide a reaction system or mixture comprising pentaborane-9 and hydrazine which is moderated with an additive such that the hydrazine is prevented from reacting as a monopropellant.

A further object of this invention is to provide a reac tion system or mixture comprising pentaborane-9 and hydrazine which is moderated with an additive such that the system is not susceptible to destructive explosions.

A still further object of the present invention is to provide a reaction system or mixture comprising pentaborane-9 and hydrazine which contains, as a moderating additive, LiB H or LlB H7 in combination with pentaborane-9 or hydrazine.

Still another object of this invention is to provide a reaction system or mixture comprising pentaborane-9 and hydlnazine which contains, as a moderating additive, LiB H or the combination of LiB,H and either hydrazine or pentaborane-9, the additive being present in an amount sufficient to prevent the heat generated by reaction of the system from reaching the decomposition temperature threshold of hydrazine.

Other objects and advantages of the present invention, it is believed, will be readily apparent from the following description thereof.

A mixture of pentaborane-9 and hydrazine is believed to function desirably as a propellant combination when atent the reaction of these materials can be controlled such that it is in accordance with the equation:

However, it is also believed that an intermediate reaction occurs according to the equation:

when pentaborane-9 and hydrazine are reacted.

The intermediate reaction designated Equation 2 is believed to be highly detrimental in that the heat of reaction thereof is believed to be sufficiently high that it exceeds the decomposition temperature threshold of hydrazine. This would, of course, result in reaction of the hydrazine as a monopropellant, which reaction does not generate as much propulsive force as the reaction with pentaborane-9. Moreover, some pentaborane-9 is thereby left unreacted and is wasted. By this mechanism the efiiciency of the overall system declines and the pentaboranehydrazine system becomes inefiicient to a degree such that it is rendered commercially undesirable. Furthermore, the reaction could proceed in such a manner that control of the hydrazine-pentaborane-9 reaction would be lost and destructive explosion would occur. The occurrence of intermediate Reaction 2 would be consistent with the reaction of pentaborane-9 and tri-methyl-amine reported, by Hough, Ford and Edwards, in Abstracts of the th American Chemical Society Meeting, Boston, April (1959), as producing the B H ztrirnethylamine adduct.

Because of the instability caused by intermediate Reaction 2, the hydrazine-pentaborane-9 system has not heretofore been successfully used as a propellant combination. Were it not for this instability, the high specific inpulse of the hydrazine-pentaborane-9 system would make it highly suitable as a propellant combination.

The present invention contemplates the addition of LiB H to the hydrazine-pentaborane-9 system to control the heat generated by the system such that the decomposition temperature threshold of hydrazine is not reached.

The salt LiB H- mixes with hydrazine releasing a smaller amount of heat than Equation 2. Furthermore, LiB H is soluble in pentaborane-9. The reaction of LiB H and N H would deliver a large amount of propulsive energy, probably according to the reaction:

Therefore, a combination of the Lil3 H -hydrazine system with the hydrazine-pentaborane-9 system in proportions such that a sutlicient amount of the former is present to prevent the latter from reaching the decomposition temperature threshold of hydrazine would create a thermodynamic balance such that almost the full potential of the pentaborane-9-hydrazine system would be realized, i.e., the complete mixing occurs at a low enough temperature such as to significantly eliminate the hydrazine reacting as a monopropellant.

For example, the lithium borane system may be added to the pentaborane system in the following manner:

LiB4H7 is mixed with pentaborane-9 in sufficient quantity that a mixture containing four mole percent LiB H and ninety-six mole percent pentaboraue-9 is obtained. The reaction mixture within the scope of the present invention may be obtained by combining this mixture with hydrazine in stoichiomctric amounts according to Equations 1 and 3.

The LiB4 H7 used in the present invention may be prepared by the reaction of B H and LiH in ether. This reaction, which also produces LiBl-I as a by-product the propellant, etc.

which may be recycled into the B H synthesis, is believed to proceed according to the equation:

on such factors as the efiiciency of the mixing jets which determine the probability of local hot spots, the ambient temperature at which the propellant is fired which depends upon the amount and type of insulation used to encase However, as previously mentioned, the qualitative amount of LiB H must be sufficient to prevent the heat generated by the system as a whole from reaching the decomposition temperature threshold of hydrazine. More than this minimum amount of LlB4H7 may be added without serious detrimental effect.

It will be obvious to one skilled in the art that the systems of the present invention have many possible applications as a fuel andsource of propulsive power, particularly in rockets and missiles.

Having fully described the present invention, it is to be understood that it is not to be limited to the details set forth, but is'of the'full scope of the appended claims.

I claim:

1. A mixture comprising pentaborane-9, hydrazine and 2. A mixture comprising pentaborane-9, hydrazine and LiB H- the LiBqHq being present in an amount sufiici'ent to prevent the heat generated by the reaction of the mixture from causing the hydrazine to react as a monopropellant.

3. A reaction system comprising reactive amounts of pentaborane-9 and hydrazine, and a reaction moderator comprising LiB H 4. The reaction system of claim 3 wherein the LiB H is present in an amount sufiicient to prevent the heat generated by the reaction of the system from reaching the decomposition temperature threshold of hydrazine.

5. The reaction system of claim 4 wherein the LiB H is present in the pentaborane-9 phase of the system.

6. A reaction system comprising reactive amounts of. pentaborane-9 and hydrazine, and a reaction moderator comprising LiB H said moderator being present in the pentaborane-9 phase of the system.

7. The reaction system of claim 6 wherein the penta- 1 borane-9 phase comprises four mole percent LlB4Hq and l ninety-six mole percent pentaborane-9.

8. A reaction system comprising reactive amounts of 'pentaborane-9 and'hydrazine, and a reaction moderator;

comprising LiB H and hydrazine.

9. The reaction system of claim 8 wherein the reaction moderator is present in an amount sufficient to prevent the heat generated by reaction of the system from reaching the decomposition temperature threshold of hydrazine.

10. A process comprising the step of reacting penta-a borane-9 with hydrazine in the presence of LiB4H7, the

LiB I-I being present in an amount sufiicient to prevent the heat generated by said reaction from reaching the decomposition temperature threshold of hydrazine.

11. The proces of claim 10 wherein the LiB I-I is present in the pentaborane-9.

12. The process of claim 11 wherein the LiB H is present in the ratio of 4 mole percent to 96 mole percent. pentaborane-9.

13. A process comprising reacting pentaborane-9 and hydrazine in the presence of a reaction moderator, said reaction moderator comprising LiB H and hydrazine, said reaction moderator being present in an amount sufiicient to prevent the heat generated by said reaction from reaching the decomposition temperature threshold of hydrazine.

No references cited.

CARL D. QUARFORTH, Primary Examiner.

LEON D. ROSDOL, Examiner. 

1. A MIXTURE COMPRISING PENTABORANE-9, HYDRAZINE AND LIB4H7. 